Many different types of building insulation are used for different types of construction. For example, in frame buildings fiberglass batts are often used in the side wall cavities and are fixed by nails or staples to the wall studs. In the ceilings, between the ceiling joints, fiberglass batts or loose fill insulation of different types are often used. Styrofoam board is another common type of building insulation which can be fitted between studs and joists or can be attached to a surface by adhesive. When completed buildings are insulated, blow-in type insulations are often used, which may be foam or loose fill fiber insulation.
While these and other types of insulation have performed satisfactorily for insulating frame buildings, newer types and methods of construction such as, for example, the open construction used with metallic buildings, do not permit the use of many of the previously known insulations. Metallic buildings, particularly those used for warehouses and/or other storage facilities, often have no ceiling. Thus, there is no suitable surface for supporting batts of insulation or the loose fill insulations. For insulating buildings with open construction, it is desirable to apply the insulation directly to the wall, roof or other surface being insulated, and to use adhesives to bond the insulation to the surface. Styrofoam boards can be used for this purpose; however, it is often difficult and time consuming to fit the boards around pipes, conduits, girders and the like. For an optimum thermal barrier the insulation should be fitted closely around any objects which intersect the surface being insulated, with no gaps through which heat transfer can occur between the insulation and the object. Spray-on insulations, which include an insulating component and an adhesive, have been used for insulating open structures, and have been applied as monolithic coatings on walls, ceilings and roofs. Cellulose fiber is often used in these types of insulation, and boric acid is added to the fiber to increase the fire resistance of the insulation. The boric acid is corrosive to metal and therefore disadvantageous when used in an insulation for metal buildings. To eliminate the corrosive effect of the boric acid, borax or other chemical agents are used to buffer the acid. Borax is expensive when compared with the other components of the insulation, and the addition of borax to boric acid containing insulators significantly increases the cost of the insulation, while contributing nothing to the heat or sound insulating qualities of the product.
Fire retardant, spray-on insulations which adhere directly to the surfaces on which they are applied have been used in the past; however, inexpensive products which can be applied easily and provide fireproofing of the area have not been available. Many of the previously used compositions of this type have been relatively heavy, thus adding substantial weight to the insulated surface. When first applied, the compositions are wet, and only thin layers, usually not more than about one inch thick, can be applied in a single application without causing areas of the applied product to sag, run or fall from the surface being insulated. Thus, to obtain a four inch thick coating of insulation, for example, four coats must be applied, allowing ample time for drying each coat before a subsequent coat is applied. This repetitive process for applying insulation adds to the cost and time required for insulating a structure since the application equipment must be set up for the separate applications, and the operator's time is increased for applying additional coats of the insulation.
Other problems have been associated with the use of spray-on type insulations which are applied directly to the surface being insulated. Many of the compositions used for such insulations fail to provide complete fireproofing, especially when only a relatively thin layer of the material is applied. It is desirable to limit the insulation coating to a thickness of approximately four inches, and to obtain therefrom a high resistance to thermal transmission. It is also desirable, in some circumstances, to achieve complete fireproofing, if possible, with a layer of only minimal thickness. Many of the compositions used previously do not provide fireproofing with a layer only four inches thick, and if thicker layers of insulation are used the insulation will often crack as a result of expansion and contraction of the surface to which it is applied. Thus, it is desirable to have a composition for insulation which will provide a fireproof barrier when used in layers of only minimal thickness, and which remains flexible when the layer is fully cured so that the insulation can bend and flex with expansion and contraction of the surface to which it is applied.
In addition to providing barriers to thermal transmission and fire spread, often it is also desirable to provide a sound absorbing barrier as well. While most insulation materials possess each of these characteristics to a greater or lesser degree, most insulation materials of the spray-on type do not possess all the characteristics to a high degree. For example, a composition highly resistant to heat transmission may not be highly resistant to flame spread. Thus, different compositions are often required, depending on the most desirable insulation characteristic.